From DE 199 33 618 A1 by the present applicant a parking lock device for an automatic transmission is known, in which when the parking lock is engaged a locking pawl that is pivotally mounted within a transmission housing engages in a parking lock gearwheel and blocks it. In this case the locking pawl is supported by means of a locking detent, relative to a guide plate which is part of a locking mechanism. When the parking lock is engaged the locking detent exerts a transverse force on the locking pawl, which is directed parallel to the axis of the parking lock bolt (pivot axis of the locking pawl). Under the action of this transverse force, the locking pawl is held against the guide plate, whereby friction forces are produced which hold up the movement of the locking pawl.
From U.S. Pat. No. 5,685,406 it is known to use rollers for reducing the friction between a locking pawl and a moving locking element. The known locking element is in the form of a locking roller arrangement which comprises a pair of rollers, one of which rests against the locking pawl and the other against an abutment fixed on the housing. In this way, when the parking lock is engaged, by virtue of rolling friction a smaller transverse force is exerted on the locking pawl. Thus, as its locking element this known device has no locking detent, but instead a locking roller.
Another problem that can arise in vehicles is that leakage currents can occur between the engine block, the starter and the transmission, which in unfavorable situations, for example if contact takes place between the locking pawl and the guide plate or the transmission housing, can lead to spark formation.